Human body communication is a technology that removes an electric cable from electronic equipments and transfers a signal through the change in electric energy by using the human body instead of the electric cable, based on the principle that the electricity flows through the human body.
In the conventional sound transmission apparatus using the human body as the transfer medium, a sound transmission is achieved in a state where both a transmission apparatus and a reception apparatus are in direct contact with the human body. The transmission apparatus transmits a sound signal, and the reception apparatus receives the signal transmitted from the transmission apparatus and converts the received signal into a signal of a frequency band capable of being sensed by people.
That is, in a conventional sound transmission apparatus, when the transmission apparatus modulates a sound signal to be transferred into a signal which is able to be transmitted through the human body and thereafter transmits the modulated signal through the human body, the reception apparatus disposed to be in contact with the vicinity of the ear of a user receives the signal which is outputted from the transmission apparatus and transmitted through the human body, and converts the received signal into a sound signal of an audio frequency band by demodulating the received signal, thus to provide an audible signal.
However, such a conventional sound transmission apparatus is provided separately with the transmission apparatus and the reception apparatus, and enables users to hear sounds only when the reception apparatus is in contact with or adjacent to the human body.
Further, with a recent increase in demand for more diverse and complicated transmission apparatuses, users desire to hear a sound signal only by making contact with an object (i.e. a chair or a multimedia player) other than the sound transmission apparatus.
For example, there has been an increasing demand of users to hear a sound signal even when the users take a seat on the chair, or come in contact with a multimedia player.
Although products using the conventional sound transmission apparatus have developed to satisfy the above-mentioned requirements, but the conventional sound transmission apparatus have problems in that users are required to carry a receiving apparatus.